scholarly journals Aqueous recognition of purine and pyrimidine bases by an anthracene-based macrocyclic receptor

2020 ◽  
Vol 56 (65) ◽  
pp. 9268-9271 ◽  
Author(s):  
Danny Van Eker ◽  
Soumen K. Samanta ◽  
Anthony P. Davis
Keyword(s):  
Hydrogen Bonding ◽  
Hydrophobic Interactions ◽  
Water Soluble ◽  
Soluble Receptor ◽  
Strong Binding ◽  
Pyrimidine Bases

Hydrophobic interactions and hydrogen bonding are preorganised to achieve strong binding by this water-soluble receptor.

Structure, stability and folding of the α-helix

2001 ◽  
Vol 68 ◽  
pp. 95-110 ◽  
Author(s):  
Andrew J. Doig ◽  
Charles D. Andrew ◽  
Duncan A. E. Cochran ◽  
Eleri Hughes ◽  
Simon Penel ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Hydrophobic Interactions ◽  
Data Bank ◽  
Site Directed Mutagenesis ◽  
Model Systems ◽  
Side Chain ◽  
Structure Stability ◽  
Helical Peptides ◽  
Vast Number ◽  
Α Helix

Pauling first described the α-helix nearly 50 years ago, yet new features of its structure continue to be discovered, using peptide model systems, site-directed mutagenesis, advances in theory, the expansion of the Protein Data Bank and new experimental techniques. Helical peptides in solution form a vast number of structures, including fully helical, fully coiled and partly helical. To interpret peptide results quantitatively it is essential to use a helix/coil model that includes the stabilities of all these conformations. Our models now include terms for helix interiors, capping, side-chain interactions, N-termini and 310-helices. The first three amino acids in a helix (N1, N2 and N3) and the preceding N-cap are unique, as their amide NH groups do not participate in backbone hydrogen bonding. We surveyed their structures in proteins and measured their amino acid preferences. The results are predominantly rationalized by hydrogen bonding to the free NH groups. Stabilizing side-chain-side-chain energies, including hydrophobic interactions, hydrogen bonding and polar/non-polar interactions, were measured accurately in helical peptides. Helices in proteins show a preference for having approximately an integral number of turns so that their N- and C-caps lie on the same side. There are also strong periodic trends in the likelihood of terminating a helix with a Schellman or αL C-cap motif. The kinetics of α-helix folding have been studied with stopped-flow deep ultraviolet circular dichroism using synchrotron radiation as the light source; this gives a far superior signal-to-noise ratio than a conventional instrument. We find that poly(Glu), poly(Lys) and alanine-based peptides fold in milliseconds, with longer peptides showing a transient overshoot in helix content.

scholarly journals The Subtleties of Dissolution and Regeneration of Cellulose: Breaking and Making Hydrogen Bonds

BioResources ◽  
2015 ◽  
Vol 10 (3) ◽  
pp. 3811-3814 ◽  
Author(s):  
Björn Lindman ◽  
Bruno Medronho
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Hydrophobic Interactions ◽  
Cellulose Dissolution ◽  
Solution Behavior ◽  
Current Discussion ◽  
Scientific Controversies ◽  
A Current

Cellulose dissolution and regeneration are old topics that have recently gained renewed attention. This is reflected in both applications – earlier and novel – and in scientific controversies. There is a current discussion in the literature on the balance between hydrogen bonding and hydrophobic interactions in controlling the solution behavior of cellulose. Some of the key ideas are recalled.

Molecular Recognition and Photoprotection of Riboflavin in Water by a Biomimetic Host

2021 ◽  
Author(s):  
Hong Zhang ◽  
Li-Li Wang ◽  
Xin-Yu Pang ◽  
Liu-Pan Yang ◽  
Wei Jiang
Keyword(s):  
Hydrogen Bonding ◽  
Molecular Recognition ◽  
Hydrophobic Effect ◽  
Water Soluble ◽  
Side Walls

A water-soluble tetralactam macrocycle with 2,6-diethoxynaphthalene group as side walls is able to strongly bind riboflavin (Ka >107 M−1) in water through hydrogen bonding and the hydrophobic effect. The encapsulated...

scholarly journals Solvation in pure and mixed solvents: Some recent developments

2007 ◽  
Vol 79 (6) ◽  
pp. 1135-1151 ◽  
Author(s):  
Omar A. El Seoud
Keyword(s):  
Hydrogen Bonding ◽  
Hydrophobic Interactions ◽  
Preferential Solvation ◽  
Mixed Solvents ◽  
Effect Of Temperature ◽  
Binary Solvent ◽  
Solvent Mixtures ◽  
Dispersion Interactions ◽  
Binary Solvent Mixtures ◽  
Recent Developments

The effect of solvents on the spectra, absorption, or emission of substances is called solvatochromism; it is due to solute/solvent nonspecific and specific interactions, including dipole/dipole, dipole-induced/dipole, dispersion interactions, and hydrogen bonding. Thermo-solvatochromism refers to the effect of temperature on solvatochromism. The molecular structure of certain substances, polarity probes, make them particularly sensitive to these interactions; their solutions in different solvents have distinct and vivid colors. The study of both phenomena sheds light on the relative importance of the solvation mechanisms. This account focuses on recent developments in solvation in pure and binary solvent mixtures. The former has been quantitatively analyzed in terms of a multiparameter equation, modified to include the lipophilicity of the solvent. Solvation in binary solvent mixtures is complex because of the phenomenon of "preferential solvation" of the probe by one component of the mixture. A recently introduced solvent exchange model allows calculation of the composition of the probe solvation shell, relative to that of bulk medium. This model is based on the presence of the organic solvent (S), water (W), and a 1:1 hydrogen-bonded species (S-W). Solvation by the latter is more efficient than by its precursor solvents, due to probe/solvent hydrogen-bonding and hydrophobic interactions. Dimethylsulfoxide (DMSO) is an exception, because the strong DMSO/W interactions probably deactivate the latter species toward solvation. The relevance of the results obtained to kinetics of reactions is briefly discussed by addressing temperature-induced desolvation of the species involved (reactants and activated complexes) and the complex dependence of kinetic data (observed rate constants and activation parameters) in binary solvent mixtures on medium composition.

scholarly journals Interaction of caldesmon with phospholipids

1993 ◽  
Vol 291 (2) ◽  
pp. 403-408 ◽  
Author(s):  
E A Czuryło ◽  
J Zborowski ◽  
R Dabrowska
Keyword(s):  
Fluorescence Spectroscopy ◽  
Hydrophobic Interactions ◽  
Tryptophan Fluorescence ◽  
Terminal Part ◽  
Strong Binding ◽  
Terminal Fragment ◽  
Electrostatic And Hydrophobic Interactions ◽  
The Stability

The interaction of caldesmon with liposomes composed of various phospholipids has been examined by tryptophan fluorescence spectroscopy. The results indicate that caldesmon makes its strongest complex with phosphatidylserine (PS) vesicles (Kass. = 1.45 x 10(5) M-1). Both electrostatic and hydrophobic interactions contribute to the stability of this complex. The site for strong binding of PS seems to be located in the N-terminal part of the 34 kDa C-terminal fragment of caldesmon. Binding of PS at this site results in displacement of calmodulin from its complex with caldesmon.

Water-Soluble Squaramide Dihydrates: N-Methylation Modulates the Occurrence of One- and Two-Dimensional Water Clusters through Hydrogen Bonding and Dipolar Interactions

2018 ◽  
Vol 18 (8) ◽  
pp. 4420-4427 ◽  
Author(s):  
Marta Ximenis ◽  
Javier Pitarch-Jarque ◽  
Salvador Blasco ◽  
Carmen Rotger ◽  
Enrique García-España ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Water Clusters ◽  
Water Soluble ◽  
Two Dimensional ◽  
Dipolar Interactions

scholarly journals Molecular Interactions of Renin with Chikusetsusaponin IV and Momordin IIc

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Hai-Ling Zhang ◽  
Gui-Lan Zhu ◽  
Xiao-Tian Chen
Keyword(s):  
Hydrogen Bonding ◽  
Binding Sites ◽  
Driving Forces ◽  
Hydrophobic Interactions ◽  
Hydrophobic Effect ◽  
Energy Calculation ◽  
Total Binding Energy ◽  
Interaction Energies ◽  
Amino Acid Residues ◽  
Poisson Boltzmann

The paper dealt with the molecular mechanism for the binding sites and driving forces of renin with chikusetsusaponin IV and momordin IIc by means of molecular docking and free energy calculation based on the crystal structure. The result showed that renin and the saponins fit well. As shown by LigPlot + software analyzing the hydrogen bonding and hydrophobic effect between renin and the saponins, the amino acid residues such as Ser230, Tyr85, and Tyr201 form the hydrogen bonds, with S3sp, S3, and S2′ being the active pockets. In addition, there are relatively strong hydrophobic interactions of renin with saponins in S3sp, S3, S2, S1, S1′, and S2′, with Gly228, Val36, Ala229, Gln19, Met303, Gln135, Ser41, Ile137, Asp38, Arg82, and Tyr83 being the key amino acids. The dynamics reached equilibration after about 1000 ps simulation with average root-mean-square deviations of 0.222 nm and 0.217 nm. The molecular mechanics Poisson–Boltzmann surface area (MM-PBSA) yielded −1.10812 kcal/mol and −39.0587 kcal/mol total binding energy for the two complexes, respectively, which were primarily contributed by electrostatic and van der Waals interaction energies, and the binding was strongly unfavored by polar solvation energy, a further confirmation that momordin IIc has stronger hydrogen bonding and hydrophobic effect in the inhibition of renin than the chikusetsusaponin IV.

Effect of aggregation of a cationic phthalocyanine in micelles and in the presence of human serum albumin

2006 ◽  
Vol 10 (01) ◽  
pp. 33-42 ◽  
Author(s):  
Myriam E. Rodriguez ◽  
Daniel A. Fernández ◽  
Josefina Awruch ◽  
Silvia E. Braslavsky ◽  
Lelia E. Dicelio
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Hydrophobic Interactions ◽  
Photophysical Properties ◽  
Sodium Dodecylsulfate ◽  
Water Soluble ◽  
Quantum Yields ◽  
Ionic Interactions ◽  
Triplet Quantum Yields

The photophysical properties of tetrakis(1,1-dimethyl-2-trimethylammonium)ethylphthalocyaninato zinc(II) tetraiodide (I) – a water-soluble cationic phthalocyanine – are presented in the presence of human serum albumin (HSA) and in micelles of sodium dodecylsulfate ( SDS ) and hexadecyltrimethylammonium chloride ( CTAC ). Spectrophotometric measurements showed that the surfactants SDS and CTAC induce monomerization of I, although the latter less efficiently than the former. This effect is less pronounced in the presence of HSA. The strength of this effect is evaluated through dimerization constants, which are Kd = (5 ± 1) × 105 m−1 in SDS , (1.5 ± 0.5) × 106 M −1 in CTAC , and (1.8 ± 0.9) × 106 M −1 in HSA. Fluorescence experiments confirm that aggregation of I drops as the concentration of surfactant is raised. Triplet quantum yields also decreased upon aggregation and were Φ T = 0.59, 0.16, and < 0.01 in SDS , CTAC , and HSA, respectively. These results indicate that the affinity of I for the environment is not just due to ionic interactions; hydrophobic interactions play an equally important role.

Palladium(II) and Platinum(II) Complexes of Novel Water-Soluble Phosphane CAP: Structure, Interligand Hydrogen-Hydrogen Bonding and in Vitro Cytotoxicity

2017 ◽  
Vol 2 (28) ◽  
pp. 8721-8725 ◽  
Author(s):  
Sergey N. Britvin ◽  
Andrey M. Rumyantsev ◽  
Anna A. Silyutina ◽  
Marina V. Padkina
Keyword(s):  
Hydrogen Bonding ◽  
In Vitro Cytotoxicity ◽  
Water Soluble

Strong binding between acidic guests and fluorescein modified -?-Cyclodextrin via hydrogen bonding

1996 ◽  
Vol 25 (4) ◽  
pp. 283-294 ◽  
Author(s):  
Fumio Hamada ◽  
Kyoko Ishikawa ◽  
Yutaka Higuchi ◽  
Youichi Akagami ◽  
Akihiko Ueno
Keyword(s):  
Hydrogen Bonding ◽  
Modified Cyclodextrin ◽  
Strong Binding
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